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21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021

作者： Uhlmann, E. Streckenbach, J. Thißen, K. Schulte Westhoff, B. Masoud, A. Maas, J. Fraunhofer Institute for Production Systems and Design Technology IPK Germany Institute for Machine Tools Factory Management IWF Technische Universität Berlin Germany Mechatronic Systems Lab. Technische Universität Berlin Germany

ISBN: (纸本)9780995775190

Typically, a large number of individual tool electrodes has to be used in sinking electrical discharge machining (sinking EDM) to successfully machine a single workpiece. Due to non-uniform wear and insufficient flushing of the working gap electrode geometries have a significant effect on the process efficiency. This paper discusses the use of an actuated variable tool electrode for sinking EDM to reduce the number of required tool electrodes and to increase the overall process efficiency. A miniaturised linear actuator was developed to individually move electrode segments to form the target shape for the tool electrode. The coordinated actuation of bundled electrode segments introduces new methods for the active flushing within the working gap, which cannot be implemented in conventional sinking EDM. Intelligent sinking strategies can further improve process efficiency by creating and sinking sub-geometries into the workpiece offering improved flushing conditions compared to the original geometry. © 2021 Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021. All rights reserved.

关键词： Electrodes

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Holistic Concept towards a Reference Architecture Model for Predictive Maintenance 54

Holistic Concept towards a Reference Architecture Model for ...

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54th CIRP Conference on Manufacturing Ssystems, CMS 2021

作者： Uhlmann, Eckart Polte, Julian Koutrakis, Nikolaos-Stefanos Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstraße 8-9 Berlin10587 Germany Technische Universität Berlin Pascalstraße 8-9 Berlin10587 Germany

In the era of digital transformation of factories, one of the most challenging applications of the Industrial Internet of Things (IIoT) is predictive maintenance. This paper presents a holistic concept for predictive maintenance together with a reference architecture that includes data acquisition on the sensor level, edge computing and digital twin applications. For that purpose, condition-based maintenance, lifecycle monitoring and digital assistance systems are integrated to develop application-specific digital twins based on the proposed architecture, integrating heterogenous data sources in order to enhance the accuracy of the machine learning models. The concept is illustrated through an experimental use case. © 2021 The Author(s).

关键词： Data acquisition

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Two-colour thermography for measurement of temperature distribution in laser beam welding

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Procedia CIRP 2024年 124卷 468-471页

作者： A. Gumenyuk N. Bakir M. Rethmeier Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany Technische Universität Berlin Pascalstrasse 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstrasse 8-9 10587 Berlin Germany

Solidification cracking is a frequently observed phenomenon in laser beam welding of austenitic stainless steels and other metallic alloys. Characterisation of cracking susceptibility requires knowledge of the precise and spatially resolved temperature distribution near the solidification front in the welding process. Thermography is a standard tool that provides a qualitative estimate of the 2D temperature field. The general disadvantage of this method is its dependence on the emission characteristics of the measured object. For welding applications, these can vary significantly in the temperature range above and below the melting temperature. For this purpose, we have developed a thermography-based measurement technique using a SWIR camera system in combination with two narrow bandpass filters that use the principle of two-wavelength pyrometry to estimate absolute temperature values. This technique was used to determine the temperature distributions and gradients near the solidification front of laser-welded austenitic steel. The results were validated by other measurements.

关键词： Type your keywords here separated by semicolons

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Comparing the performance of a nested to a continuous evolution strategy with covariance matrix adaption for optimization of drilling EDM

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Procedia CIRP 2022年 113卷 220-225页

作者： E. Uhlmann J. Streckenbach M. Polte M. Osmanovic F. Schick Institute for Machine Tools and Factory Management IWF Technische Universität Berlin Pascalstr. 8-9 10587 Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Germany

Electrical discharge machining (EDM) is a complex manufacturing process where the correlation of the individual process parameters is not fully known. When introducing new materials or complex, individual geometries in EDM, a satisfactory vector of parameters for the process must be found. This challenge is often encountered in the aerospace industry as well as in mold and tool making. One previously successful method to tackle this challenge is the stochastic optimization procedure Evolutionary Strategy (ES). Utilizing an appropriately chosen objective function, the search for a suitable vector of input parameters may be formulated as a mathematical minimization problem over the parameter space. The ES with a covariance matrix adaption (CMA) was utilized to sample from this parameter space in a stochastic manner. Examining the impact of the CMA within an ES is a promising way to gain better insight into the performance of ES. For this purpose, a vector of input parameters was optimized for a drilling EDM process with a comma and a nested comma ES with CMA. It was found that the comma ES led to a reduction in erosion duration tero of 38 % compared to the initially chosen parameters and the nested comma ES led to a reduction in erosion duration tero of 27 % compared to the same initial parameters. The additional information stored in the covariance matrix enables the ES to find a local optimum of the parameter vector faster and more consistently. This fact is verified by use of visualizations of the covariance matrix on a two-dimensional subspace. From these findings it can be concluded, that for the application of the ES to the optimization of EDM processes the CMA should be performed continuously over all generations as opposed to resetting this matrix after a number of generations.

关键词： Electrical-discharge machining Evolution strategy Optimization

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Reproducibility analysis for different numerical models and experimental setups in dry orthogonal cutting of AISI 4140 steel

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Procedia CIRP 2024年 128卷 650-655页

作者： Christian Grimm Christian Menze Jannis Saelzer Florian Sauer Rocco Eisseler Hans-Christian Möhring Volker Schulze Andreas Zabel Eckart Uhlmann Institute for Machine Tools and Factory Management (IWF) Technische Universität Berlin Pascalstr. 8-9 10587 Berlin Germany Institute for Machine Tools (IfW) University of Stuttgart Holzgartenstr. 17 70174 Stuttgart Germany Institute of Machining Technology (ISF) TU Dortmund University Baroper Str. 303 44227 Dortmund Germany Institute of Production Science (wbk) Karlsruhe Institute of Technology Kaiserstr. 12 76131 Karlsruhe Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Berlin Germany

The design of machining processes still requires iterative parameter optimisation on the real process to achieve the demanded quality. In order to use simulation results as input for models of lubricated machining processes, which is the final aim of the presented work, it is necessary to assure that already the chip forming simulations under dry conditions produce valid results. Due to extreme conditions in the chip formation zone, including high contact stresses, temperatures and deformations, advanced requirements are imposed on a numerical model. In this work, orthogonal turning of AISI 4140 steel is simulated and experimentally investigated. Aiming for a critical examination of the conventional practice to validate simulation results only through a single experimental setup, the experiments are carried out redundantly on three varying turning lathes and measurement systems. Numerical simulations are performed using finite element analysis (FEA) within the software packages ABAQUS, AdvantEdge, DEFORM and Marc, as well as meshfree methods in the form of the finite pointset method (FPM) within MESHFREE and an element-free Galerkin method (EFG) in LS-DYNA. The obtained results demonstrate the characteristics of the individual simulation methods as well as the degree of reproducibility in experiments.

关键词： Machining Simulation design informatics

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Methodology to develop Digital Twins for energy efficient customizable IoT-Products

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Procedia CIRP 2021年 98卷 258-263页

作者： Theresa Riedelsheimer Sonika Gogineni Rainer Stark Fraunhofer Institute for Production Systems and Design Technology IPK Berlin Germany Technische Universität Berlin Chair Industrial Information Technology Berlin Germany

Products are increasingly individualized and enhanced to be able to communicate, e.g. via Industrial Internet of Things (IoT). However, the impact of products on sustainability (environmental and social) across their life is often not considered and analyzed. IoT-based or smart products, that are able to communicate, generate data, which can be used to monitor and optimize sustainability indicators. The Digital Twin (DT) is a new technological concept which focuses on product individual data collection and analysis. It provides the possibility to make use of the available data and optimize the systems individual sustainability as well as future product generations. However, the design and realization of such a DT requires new approaches and capabilities, which is an identified research gap. Therefore, this paper presents a methodology to develop DTs of physical IoT-based products, the so called DT V-Model with the aim to optimize the systems sustainability, specifically environmental aspects. It is based on the V-model for the development of smart products and is enhanced with additional roles and approaches for DT development. The methodology is described in detail. The result of a development cycle according to the DT-V-Model is a tested concept of a DT, which includes Digital Master (DM) data from the planning phase and Digital Shadow (DS) data from the production, operation and End of Life-phase. For a DT for energy efficiency, the Digital Master model consists of the information and models from the product development phase including the planned production and use phase energy consumption. The Digital Shadow consists of the actual production energy consumption and the use phase energy consumption. The methodology is applied to a use case of an IoT-based consumer product that can be customized to a certain degree by the consumer. A DT is developed to monitor and optimize the products energy efficiency in production and use. The necessary elements of the DT and t

关键词： IoT-devices Digital Twin Development methodology Product service systems energy consumption

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Influence of superimposed low frequency oscillations on single-pass honing of long-chipping steel

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Procedia CIRP 2022年 108卷 607-612页

作者： E. Uhlmann A. Rozek Technische Universität Berlin Institute for Machine Tools and Factory Management (IWF) Pascalstraße 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Berlin Germany

Single-pass honing is used as a finishing process to meet high demands regarding form and dimensional accuracy of drilled bores. The disadvantages of single-pass honing compared to the conventional long-stroke honing are high process forces and torques as well as an increased risk of chip space clogging of the abrasive stones. A significant reduction in process forces and torques can be achieved by superimposing the axial movement with oscillations. In this work the kinematic basics of different oscillation parameters and their effects on single-pass honing of long-chipping steel are analyzed. It can be concluded that by superimposing low frequency oscillations in single-pass honing, the process forces and torques as well as the specific energy consumption can be reduced significantly without a decline in surface quality and form accuracy.

关键词： Surface Finish Honing Oscillation

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Micro-texture dependent temperature distribution of CVD diamond thick film cutting tools during turning of Ti-6Al-4V

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Procedia CIRP 2022年 108卷 483-488页

作者： E. Uhlmann D. Schröter E. Gärtner Technische Universität Berlin Institute for Machine Tools and Factory Management (IWF) Pascalstr. 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Berlin Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany

Machining titanium alloys such as Ti-6Al-4V results in a high thermomechanical load on cutting tools and consequently short tool lifes. With respect to a necessary reduction of the resulting cutting tool temperatures, ultrashort pulse (USP) laser fabricated micro-textured rake faces offer direct supply of cooling lubricant into the cutting zone and lead to a reduced heat induction. As a result, micro-textured CVD diamond thick film cutting tools are also capable of machining high-performance materials due to reduced contact temperatures. In the scope of the research, the resulting temperature distribution for micro-textured rake faces will be compared under both dry and wet process conditions. Measurements show a reduction of the resulting cutting tool temperatures of Δ ϑt = 27.9 % using micro-textured cutting tools compared to non-textured cutting tools. A validated simulation provides valuable information about the contact temperatures enabling a specific development of the micro-texture geometry. As a result, a reduction of the contact temperature between chip and rake face by Δ ϑ T = 24.7 % was possible.

关键词： diamond tool texture titanium turning temperature laser surface integrity

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Residual stress assessment during cutting tool lifetime of CVD-diamond coated indexable inserts

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Procedia CIRP 2022年 108卷 799-804页

作者： E. Uhlmann D. Hinzmann Technische Universität Berlin Institute for Machine Tools and Factory Management (IWF) Pascalstr. 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Berlin Germany

Insufficient coating adhesion limits reproducibility regarding tool lifetime as well as workpiece quality during the application of CVD-diamond coated cutting tools. Depending on the combination of tungsten carbide substrate material, coating thickness as well as coating morphology, individual residual stress conditions exist within CVD-diamond coated cutting tool specifications. The application of these tools is accompanied by coating delamination as primary cutting tool failure. The tool lifetime of the respective cutting tool composition depends on the corresponding residual stress condition until crack development within the CVD-diamond coating initiates tool failure. During external cylindrical turning of hypereutectic aluminium silicon alloy AlSi17Cu4Mg-T6 the residual stress condition of a CVD-diamond coated cutting tool is assessed along the cutting edge, the rake face as well as flank face throughout the respective tool lifetime. Consequently, the progression of the residual stress condition until cutting tool failure regarding coating delamination is observed. During the tool lifetime of the investigated CVD-diamond cutting tools, compressive residual stress ∆σ R,c shifts to tensile residual stress ∆σ R , t underneath the cutting edge corner. The approximated residual stress difference of ∆σ R ≈ 5 GPa indicates stress peak relaxation processes, such as crack initiation, within the CVD-diamond coating.

关键词： diamond tool residual stress aluminum turning

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Experimental investigations of the workpiece-media-interaction and the surface topography formation in centrifugal disc finishing

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Procedia CIRP 2022年 115卷 24-29页

作者： Marco Kopp Eckart Uhlmann Christian Kneider Technische Universität Berlin Institute for Machine Tools and Factory Management (IWF) Pascalstr. 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Berlin Germany

In this study the workpiece-media-interaction in centrifugal disc finishing is investigated using a miniaturised free movable force measuring system. Characteristics of the workpiece-media-interaction are derived and correlated with the surface topography formation of Ti-6Al-4V workpieces. As a result, it was found that characteristics of the workpiece-media-interaction such as the contact force between the media and the workpiece, the contact duration and the contact frequency are dependent on the type of media as well as the rotational speed of the disc. Consequently, both, the type of media as well as the rotational speed of the disc have an influence on the resulting surface roughness.

关键词： centrifugal disc finishing contact forces topography formation

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